- The Washington Times - Tuesday, December 5, 2006

We are overwhelmed with nutritional advice. Diet books are best sellers. Nutritional gurus eat up television time, and the Internet is full of free advice for anyone who can Google “weight loss.”

Unfortunately, we get an abundance of conflicting advice. What is true about low-fat diets versus low-carb diets? Why do we have so much conflicting information about food and eating?

My work as the medical director of a weight management program puts me almost continuously in the confusion of conflicting, but otherwise seemingly reasonable scientific advice. Whether I’m working with patients losing weight, or with companies trying to find new medications or ingredients, what is clear is that the science is always exciting, but that the excitement creates an abundance of confusion. Studies are contradicted by other studies, or selectively reinterpreted by experts or quasi-experts.

There’s value in looking at a couple of these conflicts more carefully. If we analyze them, we can start to see why there is confusion, and why reasonable people can disagree.

What’s best for weight loss? Are we better trying a low-carb diet (like Atkins or South Beach) or a low-fat diet (the standard approach)? It seems likely that there’s value in both, reasonable arguments for each, and either can be useful. It’s not so much that they contradict each other, but that they are simply different ways of doing what is important: decreasing the number of calories you consume. It’s not necessarily one or the other, but one is a bit more gimmicky and one is more traditional. You choose what can be helpful for you.

There’s an advantage in a low-carb diet; cutting down on your carbohydrates while you increase your protein. The benefit probably does not relate to how carbohydrates affect insulin. Instead, it does seem that there’s reasonable evidence that maintaining a diet which has a relatively high ratio of protein to carbohydrate calories suppresses hunger. People on this diet seem to be a bit more comfortable. While a relatively high fat diet is not a program that you’d want to use for the long term, it may be a good way of losing weight so that you can get to a better baseline for the ongoing struggle.

The alternative, cutting fat intake, also makes sense. Each ounce of fat contains more than twice as many calories as an ounce of carbohydrate. And fat is easy for your body to store; the storage of carbohydrates is much more complicated. Fat as food is easy to convert to the flab on your abdomen. Your metabolism has to spend calories to convert consumed carbohydrate to stored fat; a much more complex metabolic process.

It is not that one diet is right and the other is wrong. Neither will solve the problem. The basics are still true: weight loss requires fewer calories consumed or more calories spent in activity. Both diets can be useful in the difficult task of decreasing calories consumed.

Is one type of sweetener better than another? After all that has been said and written about sugar, high fructose corn syrup (HFCS) and the artificial sweeteners, we still have confusion and uncertainty about what is best and what is safe. Does it make any difference how we sweeten our food, our coffee or our soft drinks? No, it probably makes no difference. Sugar works well, and so too do the sugar alternatives and the artificial sweeteners.

Much of the recent controversy focuses on HFCS. About 25 years ago, food companies started using high fructose corn syrup (HFCS), a sweetener derived from corn, as a substitute for sugar in soft drinks and many other foods. HFCS is the chemical and nutritional equivalent of table sugar (sucrose). The two substances have the same calories, the same chemical composition and are metabolized identically. HFCS is a mixture of two carbohydrate molecules, glucose and fructose. Table sugar is a chemical combination of the same two molecules in a form that is rapidly, efficiently and completely digested and forms an equivalent mixture of glucose and fructose. HFCS and sugar have an equal effect on feelings of fullness and satiety.

The increase in the prevalence of obesity in the U.S. coincides with the increased use of HFCS and it is tempting for some of the experts to pose the obvious question: Does HFCS cause obesity? We know, of course, that the simultaneous occurrence of two events does not necessarily mean that one caused the other and, in the case of HFCS, it is fair to say that there is no causal relationship between the two. The prevalence of obesity and diabetes is increasing even more rapidly in parts of the world where HFCS is not used in any significant amounts.

That doesn’t mean that you can consume unlimited amounts of sugar or HFCS. Both contain the same number of calories, but there’s nothing ominous about either. Just like all of life and eating, moderation is obligatory.

There are dozens of other conflicts in nutrition, and usually the explanation is not as complex as the extreme view on one side or the other would have you believe. Usually these conflicts arise because of incomplete information. We simply do not have enough scientific studies to answer the question unambiguously. We need more information, better research, and more complex analysis of the issues.

What can we do about making food decisions? How can a reasonable person make a judgment about what to do?

1. Do not expect perfection. This is an often neglected phenomenon of science. Absolute clarity on any issue is rare. Tolerate some ambiguity.

2. Some things, particularly about food and nutrition, are still unknown. We’ve accomplished a lot, but a great deal needs still to be learned. Time often resolves the issues. What seems confusing now may be very clear in 10 years.

3. Use your good judgment. Radical food changes are rarely necessary but sometimes changes in food behavior seem reasonable and can be justified. My grandmother was a wise woman and so was my mother, but they were not always right. I don’t think I could survive a regular diet of what was standard in my grandmother’s home.

4. Be skeptical. Wisdom is uncommon. Absolute wisdom is rare.

5. Don’t overuse any single food or food group. Exercise. And don’t believe everything you read.

Dr. Arthur Frank is medical director of the George Washington University Weight Management Program, a member of the Scientific Advisory Board of the Corn Refiners Association, and author of numerous scientific papers on obesity, weight management, food and nutrition.



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